feat(CDA): Add asset localisation support

CHANGELOG.md

@@ -2,11 +2,15 @@
 #### Date: Feb-10-2026
 
 ##### Feat:
-- CDA / DAM 2.0 – AssetFields support
+- CDA / – AssetFields support
   - Added `AssetFields(params string[] fields)` to request specific asset-related metadata via the CDA `asset_fields[]` query parameter
   - Implemented on: Entry (single entry fetch), Query (entries find), Asset (single asset fetch), AssetLibrary (assets find)
   - Valid parameters: `user_defined_fields`, `embedded_metadata`, `ai_generated_metadata`, `visual_markups`
   - Method is chainable; when called with no arguments, the query parameter is not set
+- CDA / – Asset localisation support
+  - Added `SetLocale(string locale)` on Asset for single-asset fetch by locale (e.g. `stack.Asset(uid).SetLocale("en-us").Fetch()`)
+  - Added `Title` property on Asset for localised title in API response
+  - AssetLibrary `SetLocale` continues to support listing assets by locale
 
 ### Version: 2.25.2
 #### Date: Nov-13-2025

Contentstack.Core.Tests/AssetTest.cs

@@ -1133,5 +1133,124 @@ public async Task AssetFields_AssetLibrary_WithEmptyArray_RequestSucceeds()
                 Assert.Fail("AssetLibrary.FetchAll with AssetFields(empty array) did not return a result.");
             Assert.NotNull(assets.Items);
         }
+
+        [Fact]
+        public async Task FetchAssetsWithLocale_ReturnsLocalisedAssets()
+        {
+            var locale = "en-us"; // or "ar" if your stack has that locale
+            ContentstackCollection<Asset> assets = await client.AssetLibrary()
+                .SetLocale(locale)
+                .FetchAll();
+
+            Assert.True(assets.Items != null);
+            if (assets.Items.Count() == 0)
+                return; // no assets in this locale
+
+            foreach (Asset asset in assets)
+            {
+                // Root-level locale (when API returns it)
+                var rootLocale = asset.Get("locale");
+                if (rootLocale != null)
+                    Assert.Equal(locale, rootLocale.ToString());
+
+                // Or via publish_details (existing pattern from FetchAssetsPublishWithoutFallback)
+                var publishDetails = asset.Get("publish_details") as JObject;
+                if (publishDetails != null && publishDetails["locale"] != null)
+                    Assert.Equal(locale, publishDetails["locale"]?.ToString());
+            }
+        }
+
+        /// <summary>
+        /// Asset localisation: Fetch single asset with locale query param; response has requested locale.
+        /// </summary>
+        [Fact]
+        public async Task FetchSingleAssetWithLocale_ReturnsLocalisedAsset()
+        {
+            string uid = await FetchAssetUID();
+            var locale = "en-us";
+
+            Asset asset = await client.Asset(uid).AddParam("locale", locale).Fetch();
+
+            Assert.NotNull(asset);
+            Assert.NotNull(asset.Uid);
+            var publishDetails = asset.Get("publish_details") as JObject;
+            if (publishDetails != null && publishDetails["locale"] != null)
+                Assert.Equal(locale, publishDetails["locale"]?.ToString());
+            var rootLocale = asset.Get("locale");
+            if (rootLocale != null)
+                Assert.Equal(locale, rootLocale.ToString());
+        }
+
+        /// <summary>
+        /// Asset localisation: List assets with SetLocale("ar"); each asset has locale in response.
+        /// </summary>
+        [Fact]
+        public async Task FetchAssetsWithLocaleAr_ReturnsAssetsWithLocale()
+        {
+            ContentstackCollection<Asset> assets = await client.AssetLibrary()
+                .SetLocale("ar")
+                .Limit(10)
+                .FetchAll();
+
+            Assert.NotNull(assets.Items);
+            if (assets.Items.Count() == 0)
+                return; // stack may not have assets in "ar"
+
+            foreach (Asset asset in assets)
+            {
+                var publishDetails = asset.Get("publish_details") as JObject;
+                if (publishDetails != null && publishDetails["locale"] != null)
+                    Assert.Equal("ar", publishDetails["locale"]?.ToString());
+                var rootLocale = asset.Get("locale");
+                if (rootLocale != null)
+                    Assert.Equal("ar", rootLocale.ToString());
+            }
+        }
+
+        /// <summary>
+        /// Asset localisation: SetLocale with IncludeFallback returns assets; locale in publish_details.
+        /// </summary>
+        [Fact]
+        public async Task FetchAssetsWithLocaleAndFallback_ReturnsLocalisedOrFallback()
+        {
+            var locale = "en-us";
+            ContentstackCollection<Asset> assets = await client.AssetLibrary()
+                .SetLocale(locale)
+                .IncludeFallback()
+                .Limit(10)
+                .FetchAll();
+
+            Assert.NotNull(assets.Items);
+            if (assets.Items.Count() == 0)
+                return;
+
+            foreach (Asset asset in assets)
+            {
+                var publishDetails = asset.Get("publish_details") as JObject;
+                Assert.NotNull(publishDetails);
+                Assert.NotNull(publishDetails["locale"]);
+            }
+        }
+
+        /// <summary>
+        /// Asset localisation: Single asset fetch using Asset.SetLocale returns localised asset.
+        /// </summary>
+        [Fact]
+        public async Task FetchSingleAssetWithSetLocale_ReturnsLocalisedAsset()
+        {
+            string uid = await FetchAssetUID();
+            var locale = "ar";
+
+            Asset asset = await client.Asset(uid).SetLocale(locale).Fetch();
+
+            Assert.NotNull(asset);
+            Assert.NotNull(asset.Uid);
+            var publishDetails = asset.Get("publish_details") as JObject;
+            if (publishDetails != null && publishDetails["locale"] != null)
+                Assert.Equal(locale, publishDetails["locale"]?.ToString());
+            var rootLocale = asset.Get("locale");
+            if (rootLocale != null)
+                Assert.Equal(locale, rootLocale.ToString());
+        }
     }
 }

Contentstack.Core.Unit.Tests/AssetLibraryUnitTests.cs

@@ -333,6 +333,43 @@ public void SetLocale_AddsQueryParameter()
             Assert.Equal(locale, urlQueries?["locale"]?.ToString());
         }
 
+        /// <summary>
+        /// Asset localisation: SetLocale with locale "ar" adds locale query param for API.
+        /// </summary>
+        [Fact]
+        public void SetLocale_ForAssetLocalisation_AddsLocaleQueryParameter()
+        {
+            var assetLibrary = CreateAssetLibrary();
+            var locale = "ar";
+
+            AssetLibrary result = assetLibrary.SetLocale(locale);
+
+            Assert.NotNull(result);
+            Assert.Same(assetLibrary, result);
+            var urlQueriesField = typeof(AssetLibrary).GetField("UrlQueries",
+                BindingFlags.NonPublic | BindingFlags.Instance);
+            var urlQueries = (Dictionary<string, object>)urlQueriesField?.GetValue(assetLibrary);
+            Assert.True(urlQueries?.ContainsKey("locale") ?? false);
+            Assert.Equal("ar", urlQueries?["locale"]?.ToString());
+        }
+
+        /// <summary>
+        /// SetLocale when called again updates the locale query param (overwrite).
+        /// </summary>
+        [Fact]
+        public void SetLocale_UpdatesLocaleWhenCalledAgain()
+        {
+            var assetLibrary = CreateAssetLibrary();
+            assetLibrary.SetLocale("ar");   
+            assetLibrary.SetLocale("en-us");
+
+            var urlQueriesField = typeof(AssetLibrary).GetField("UrlQueries",
+                BindingFlags.NonPublic | BindingFlags.Instance);
+            var urlQueries = (Dictionary<string, object>)urlQueriesField?.GetValue(assetLibrary);
+            Assert.True(urlQueries?.ContainsKey("locale") ?? false);
+            Assert.Equal("ar", urlQueries?["locale"]?.ToString());
+        }
+
         #endregion
 
         #region AddParam Tests

Contentstack.Core.Unit.Tests/AssetUnitTests.cs

@@ -533,6 +533,68 @@ public void AddParam_AddsQueryParameter()
 
         #endregion
 
+        #region Asset Locale Tests (single-asset fetch with locale)
+
+        /// <summary>
+        /// Asset.SetLocale adds locale query param for single-asset fetch.
+        /// </summary>
+        [Fact]
+        public void SetLocale_AddsQueryParameter()
+        {
+            var asset = CreateAsset();
+            var locale = "en-us";
+
+            Asset result = asset.SetLocale(locale);
+
+            Assert.NotNull(result);
+            Assert.Same(asset, result);
+            var urlQueriesField = typeof(Asset).GetField("UrlQueries",
+                BindingFlags.NonPublic | BindingFlags.Instance);
+            var urlQueries = (Dictionary<string, object>)urlQueriesField?.GetValue(asset);
+            Assert.True(urlQueries?.ContainsKey("locale") ?? false);
+            Assert.Equal("en-us", urlQueries?["locale"]?.ToString());
+        }
+        /// <summary>
+        /// Asset localisation: AddParam("locale", "ar") adds locale query for single-asset fetch.
+        /// </summary>
+        [Fact]
+        public void AddParam_WithLocale_AddsLocaleQueryParameter()
+        {
+            var asset = CreateAsset();
+            var locale = "ar";
+
+            Asset result = asset.AddParam("locale", locale);
+
+            Assert.NotNull(result);
+            Assert.Same(asset, result);
+            var urlQueriesField = typeof(Asset).GetField("UrlQueries",
+                BindingFlags.NonPublic | BindingFlags.Instance);
+            var urlQueries = (Dictionary<string, object>)urlQueriesField?.GetValue(asset);
+            Assert.True(urlQueries?.ContainsKey("locale") ?? false);
+            Assert.Equal("ar", urlQueries?["locale"]?.ToString());
+        }
+
+        /// <summary>
+        /// Single-asset fetch: locale can be combined with include_fallback.
+        /// </summary>
+        [Fact]
+        public void AddParam_LocaleWithIncludeFallback_AddsBothQueryParameters()
+        {
+            var asset = CreateAsset();
+
+            asset.AddParam("locale", "en-us").IncludeFallback();
+
+            var urlQueriesField = typeof(Asset).GetField("UrlQueries",
+                BindingFlags.NonPublic | BindingFlags.Instance);
+            var urlQueries = (Dictionary<string, object>)urlQueriesField?.GetValue(asset);
+            Assert.True(urlQueries?.ContainsKey("locale") ?? false);
+            Assert.Equal("en-us", urlQueries?["locale"]?.ToString());
+            Assert.True(urlQueries?.ContainsKey("include_fallback") ?? false);
+            Assert.Equal("true", urlQueries?["include_fallback"]?.ToString());
+        }
+
+        #endregion
+
         #region SetHeader and RemoveHeader Tests
 
         [Fact]

Contentstack.Core/Models/Asset.cs

@@ -118,6 +118,12 @@ public string Url
         /// </summary>
         public string Description { get; set; }
 
+        /// <summary>
+        /// Localized title of the asset (e.g. when fetched with SetLocale / asset localisation).
+        /// </summary>
+        [JsonProperty(PropertyName = "title")]
+        public string Title { get; set; }
+
         /// <summary>
         /// Set array of Tags
         /// </summary>
@@ -319,6 +325,28 @@ public Asset AssetFields(params string[] fields)
             return this;
         }
 
+        /// <summary>
+        /// Sets the locale for fetching this asset. Returns the asset in the specified locale.
+        /// </summary>
+        /// <param name="locale">Locale code (e.g. "en-us", "ar").</param>
+        /// <returns>Current instance of Asset for chaining.</returns>
+        /// <example>
+        /// <code>
+        ///     var asset = await stack.Asset(uid).SetLocale("en-us").Fetch();
+        /// </code>
+        /// </example>
+        public Asset SetLocale(string locale)
+        {
+            if (!string.IsNullOrEmpty(locale))
+            {
+                if (UrlQueries.ContainsKey("locale"))
+                    UrlQueries["locale"] = locale;
+                else
+                    UrlQueries.Add("locale", locale);
+            }
+            return this;
+        }
+
 
         public void RemoveHeader(string key)
         {